Can somebody answer these questions for me?

So yeah, I've been busy very much and just came online on steam and steamgifts day before, and yesterday. I noted some new things overall, and would like to ask you some questions (If you'd be most polite to answer them)

-What is with Dishonored GotY's price on Steam Trades? I was looking for a copy and was expecting something like 16 TF2 keys, but it is going for 7 and quite a lot of people have posted that they have a copy to trade. Was there any discount on the same?

-What is with these "Doge" memes? A picture of a dog with some random words written. I mean, what's the point? I couldn't understand what it all meant. Yeah, I did consult knowyourmeme, but it was more history than actual explanation

Would someone please clarify? Thanks!